This invention relates to a method for processing photographic material. In particular, the invention relates to a method of processing which uses a low volume of processing solution.
Conventional processing of photographic material requires the use of large tanks of processing solutions. Each tank contains a processing solution such as developer, bleach, fixing solution or washing solution. The material is transported through each tank in turn, typically in a sinusoidal manner. There is a tendency for the solutions to carry over from one tank to another leading to pollution of the solutions. Conventional processing has several other drawbacks. The temperatures which can be utilised are limited and therefore the process is slow. The composition of the solutions must be stable over long time periods in the processing tanks. Replenishment of the solutions is difficult to control. The processing apparatus is also very large due to the number of processing tanks.
An alternative process uses a single tank which is filled with the first processing solution, emptied, filled with a second processing solution and so on until the process is completed. Again, this process uses relatively large volumes of processing solution and contamination of one solution by another needs to be carefully avoided.
To overcome the problems of conventional deep tank processing surface application of the processing chemicals was developed. In previous surface application methods a volume of solution is applied to the surface of the material being processed. However, previous surface application methods have several drawbacks. If the solution applied to the material is just left on the material in a static condition the processing will be very slow and inefficient because there is no agitation and by-products accumulate in the material layers and slow down processing. This method is also prone to non-uniformity of processing.
It is also known to process a photographic material within a rotary tube. The material to be processed is placed emulsion side facing inwards within the tube. Solution is added and the tube rotated. Large volumes of processing solution (750 ml/m2 and upwards) will process the material effectively so long as rotation is not so fast as to cause dispersion of the solution puddle. Rapid rotation of the device is however very desirable to quickly and evenly distribute a given small volume of solution over the whole surface of the material so that processing is uniform from one end to the other. If the rotation is too slow there will be seasoning of the small volume of solution by the front end of the material and processing will be different at the back end of the material. Small volumes of processing solution (540 ml/m2 or less) do not properly process film or paper because when the device is rotated, even at low speeds of rotation, the solution puddle is dispersed and spread over the whole surface of the material. Consequently there is no agitation. This leads to several processing defects. Processing is streaky, non-uniform and also slow because of local consumption and the accumulation of by-products. There is no surface mixing and chemical economy is therefore low.
In color negative film processing carried out in small continuous processors or xe2x80x9cminilabsxe2x80x9d the film passes through each stage of the process and from one tank of processing solution to the next tank of processing solution in a sinusoidal manner. The C-41RA process has the following process cycle and replenishment volumes, see Z-131 Manual xe2x80x9cUsing Kodak Flexicolor Chemicalsxe2x80x9d:
Another process which uses even smaller volumes to replenish uses the Kodak Flexicolor SM Chemicals, see Manual Z-101, xe2x80x9cUsing Kodak SM Chemcials in SM Minilabsxe2x80x9d.
where ml/linear meter refers to ml/linear meter of 35 mm film. These volumes are representative of the smallest volumes needed to process film in existing commercial processors. The processing tanks used in a xe2x80x9cminilabxe2x80x9d processor are usually within the range of 3 to 20 liters volume for each tank depending on the individual design. In Process C-41SM the developer stage has one tank, the bleach stage has one tank, the fixer stage consists of two tanks and the stabiliser stage consists of three tanks. This gives the total number of tanks as seven. It can be seen that each processing solution is in at least one separate tank and the film passes sequentially through these tanks.
Contamination of a given tank of processing solution by carry-over from a previous tank of processing solution is inevitable in a conventional processor. It is usual practice to minimise contamination due to carry-over by providing squeegee rollers before the cross over. Accidental contamination of one processing solution will sometimes occur by splashing or careless filling of a processor. Contamination of the developer solution by fixer solution or bleach solution must be avoided since otherwise the performance and stability of the developer solution will be seriously reduced even to the point of being unacceptable. In the conventional processing method it is possible to generate unacceptable colored stains if the developer solution is contaminated with bleach or fix solution. Such unacceptable colored stains can arise from quite moderate amounts of contamination. For example, a few ml of fixer solution per liter of developer solution can increase the stain level so that the process is unacceptable.
It is an aim of the invention to reduce the total volume of processing solutions used to process a photographic material.
The invention provides a method for processing a silver halide photographic material comprising the steps of loading the material into a chamber adapted to hold the material therein, introducing a metered amount of a first processing solution into the chamber, processing the photographic material with the first processing solution, introducing a metered amount of a second processing solution which is other than a second part of the first processing solution into the chamber without removing the first processing solution so that at least part of the whole volume of the second processing solution is provided by the first processing solution and processing the photographic material with the second processing solution, the whole volume of solution for each processing stage being spread over the whole area of the photographic material in a repetitive manner to enable uniform processing.
By making use of the volume of a preceding solution to conserve the total volume of processing solutions used, the total volume of processing solutions used to process a photographic material is very low. A first processing solution having a volume similar to the standard replenishment volume may be used to process a photographic material in a small volume single use processor. Under normal circumstances, the volume remaining after the first stage of such a single use process would be discarded. In the present invention, this volume is left in the tank and a concentrated solution of the next processing solution is added to it in order to convert it into the second processing solution. The second processing solution may then be converted into a third processing solution by the addition of another concentrated solution again without removal of the second processing solution, and so on until the wash stage is reached.